Time Zones - Calculator

Calculates the time of day of time zones from the difference to the world time (UTC). The current world time is displayed and as example Central European Time (+1, CET) or Central European Summer Time (+2, CEST). Enter a world time and the difference of one or two times zones, whose time will be calculated and if it is on the same day (today) or another (yesterday, tomorrow).

Some important time zones are:
Japan Standard Time (JST): +9h
China Standard Time (CST): +8h
India Standard Time (IST): +5h30min
Moscow Standard Time (MST): +3h
Central European Time (CET): +1h
Greenwich Mean Time (GMT): ±0h
Eastern Standard Time: (EST): -5h
Pacific Standard Time (PST): -8h
For the time zones of the world, see table of time zones.

If in the according country daylight saving time (summer time) is active, one hour is added (+1h).

Each country can choose its own time zone. Large countries, those with a large east-west distance, can be located in multiple time zones, but they don't have to be. Countries with multiple time zones are Russia (11), USA (6), Canada (6), Brazil (4), Mexico (4), Australia (3), Indonesia (3), and Kazakhstan (2). If overseas territories are included, France has the most time zones with 12. Vast China has only one time zone, which refers to Beijing, which is located to the east. So, when it is officially midday in western China, it is actually still morning there.
Most time zones are spaced at multiples of one hour from Greenwich Mean Time. Some are spaced every half hour, as in India. On the equator, one-hour intervals would correspond to the Earth's circumference of 40075 kilometers divided by 24, or about 1670 kilometers of width per time zone, if they were regular. At a different latitude, this would be the rotational circumference divided by 24. Of course, time zones are not regular, but mostly run along the borders of countries, continents and cultural areas.